The present invention relates to a barrel assembly for an electromagnetic rail gun.
One proposed rail gun, described in copending U.S. patent application Ser. No. 506,430, which has been assigned commonly with the present application, includes an elongated barrel which has a pair of longitudinally extending parallel conductors or rails disposed symmetrically about its axis. The rails are separated from one another by elongated insulating members disposed circumferentially between the rails. The rails and insulators are disposed within an elongated tube and prestressed by a pressure medium disposed radially outwardly of the rails and insulating members within the tube. In one embodiment, the pressure medium is a resin which is injected as a liquid, pressurized, and cured to solid phase.
The rails are connected at their rearward or breech ends to opposite terminals of a source of direct current. A circuit through the rails may be completed either by a conductor disposed between the rails or by a plasma arc between the rails. This results in the flow of current which generates magnetic flux between the rails. The flux cooperates with the current in the conductor or the plasma to accelerate the conductor or plasma forward between the rails. The projectile may include the conductor or may be positioned forward of the conductor or plasma arc and driven forward thereby.
In addition to accelerating the projectile forward, electromagnetic forces generated during firing of the rail gun include bursting forces which push outwardly on the rails. Additional bursting forces, acting on both the rails and the insulators, may result from gas pressure generated in the barrel during firing. The gas pressure may be particularly high in barrels of rail guns wherein a plasma arc completes the circuit between the rails, due to the vaporization of metal during the initiation of the arc. Past attempts to construct rail gun barrels suitable for firing projectiles at high velocity have often been unsuccessful, largely due to inability of the barrel components to withstand the bursting forces during firing. Various types of failures may occur during firing, and the nature of the various stresses acting on the barrel during firing has not been entirely understood.